Harry Ralph Ricardo. 26 January 1885 -- 18 May 1974

Harry Ralph Ricardo was born at a time when mechanical engineering was developing from a craft into a technology. The steam engine, the prime mover of the day, was only beginning to be threatened by the steam turbine, and the internal combustion engine was in its infancy. This engine was to become his lifelong interest. He brought to it not only the skill of an outstanding designer, which was soundly based on personal craftsmanship, but also a long lasting curiosity and originality in engineering research. His contributions to the understanding of the ignition, combustion and detonation processes in spark- ignition and diesel engines were of the greatest importance; he gave the world the concept of the octane number as a means of rating the tendency of fuels to detonate. His application of this knowledge and his ability in design is seen not only in his early engines, for example in the two-stroke cycle Dolphin and the four-stroke cycle engine for the tanks in 1917, but in his light high speed diesel engines, the prime mover of the modern truck, and the sleeve valve aero-engines which were the last and best of the large British piston engines for aircraft.